The present invention relates to depth control of thread cutting spindles, and more particularly to depth control of tapping spindles.
Automatic depth control of tapping spindles is exemplified in U.S. Pat. No. 3,791,756 where pins in the spindle stem engage in slots to drive a driven sleeve member. When the tapping progresses to a predetermined depth, this engagement is released to stop the tapping. The bottom sides of the sleeve member have round edges so that the pins will slide along the bottom sides of the sleeve. This produces axial reciprocation even after the spindle stem is stopped since the sleeve is forced toward the pins by a spring and the rotating. Special mechanism or means and undesirable space or length are required for this axial reciprocation, resulting in lengthening of the spindle and restricting acceptable work-pieces to small sizes.